Elections were held for all 435 seats representing the 50 U.S. states and also for the delegates from the District of Columbia and five major U.S. territories.

Although Democratic candidates received a nationwide plurality of more than 1.4 million votes (1.1%) in the aggregated vote totals from all House elections,[3] the Republican Party won a 33-seat advantage in seats, thus retaining its House majority by 17 seats.

[4] This disparity — common in close elections involving single-member district (especially plurality) voting[5] — has sometimes been attributed to targeted Republican gerrymandering in the congressional redistricting process following the 2010 United States Census.

The previous four times were in 1914, 1942, 1952, and 1996; in the former two elections, Democrats won the House majority without winning the popular vote, whereas in the latter two, the Republicans did so.

With the Democrats' simultaneous victories in both of New Hampshire's congressional districts, this was also the last time either party flipped control of an entire House delegation.

An additional Republican incumbent, Gary Miller, won re-election in an entirely different district from the one he had previously represented.

As a result of the Fair Districts Amendment, approved by voters via referendum in 2010, the legislature could not take incumbency into account in drawing the lines.

[58] As a result, two incumbent Republicans, John Mica and Sandy Adams, were drawn into the same district, creating a third new seat.

Illinois lost one seat in reapportionment, forcing a pair of incumbent Republicans into the same district.

Iowa lost one seat in reapportionment, forcing a pair of incumbents, a Democrat and a Republican, into the same district.

Louisiana lost one seat in reapportionment, forcing a pair of incumbent Republicans into the same district.

Massachusetts lost one seat in reapportionment, forcing a pair of incumbent Democrats into the same district, although one, John Olver, retired in advance of the legislature's approval of new maps.

Missouri lost one seat in reapportionment; two Democrats were drawn into the same district as a result.

After the legislature failed to reach agreement, New York conducted its 2012 congressional elections under a map drawn by a federal magistrate judge.

[62] A third incumbent impacted by redistricting, Gary Ackerman, chose to retire, creating an open seat.

After the initial redistricting map drawn by the Texas Legislature was denied pre-clearance by a federal district court under Section 5 of the Voting Rights Act, Texas conducted its 2012 congressional elections under a court-ordered interim map.